An electrical relay is a device that enables a connection to be made between two electrodes in order to transmit a current. Some relays include a coil and a magnetic switch. When current flows through the coil, a magnetic field is created proportional to the current flow. At a predetermined point, the magnetic field is sufficiently strong to pull the switch's movable contact from its rest, or de-energized position, to its actuated, or energized position pressed against the switch's stationary contact. When the electrical power applied to the coil drops, the strength of the magnetic field drops, releasing the movable contact and allowing it to return to its original de-energized position. As the contacts of a relay are opened or closed, there is an electrical discharge called arcing, which may cause heating and burning of the contacts and typically results in degradation and eventual destruction of the contacts over time.
A solenoid is a specific type of high-current electromagnetic relay. Solenoid operated switches are widely used to supply power to a load device in response to a relatively low level control current supplied to the solenoid. Solenoids may be used in a variety of applications. For example, solenoids may be used in electric starters for ease and convenience of starting various vehicles, including conventional automobiles, trucks, lawn tractors, larger lawn mowers, and the like.
A normally open relay is a switch that keeps its contacts closed while being supplied with the electric power and that opens its contacts when the power supply is cut off. Currently, most normally open relays have limited operating voltage ranges. For example, normally open relays are limited to operate in either a nominal 12 or 24 volt ranges. Other relays today can operate over a wider voltage range, e.g., between 5 v and 32 v. However, on the low end of the voltage range, a normally open relay may chatter due to a weak magnetic holding force. At the high end of the voltage range, the relay will consume a large amount of energy and produce an excessive amount of heat due to current constantly flowing in the coil windings. This leads to an increased overall size of the relay when compared to a similarly rated bi-stable relay due to the need for the coil windings required to support the constant current.
Thus, a need exists for an improved bi-stable electrical solenoid switch having a constant current source capable of operating in a constant current mode allowing for a wide operating voltage range and a lower operating power. It is with respect to these and other considerations that the present improvements are provided.